This arrest is outrageous. No doubt the police will claim they have a duty to investigate the leaking of sensitive Government information. Of course, they're right..

I can only presume that as soon as they've finished with Damien Green, they'll be racing round to 11 Downing Street to raid Alistair Darling's home, as part of their investigation into how sensitive Government information, the key measures from the Pre-Budget Report, leaked.

While they have Alistair Darling in custody, perhaps they can ask him who blabbed price-sensitive information concerning Northern Rock, The Lloyds/HBOS merger and the Bank Recapitalisations to the BBC's Robert Preston.

But they won't arrest Darling.

Leaks that are useful to the Labour Government will be ignored.

Leaks that embarrass the Labour Government will be investigated with the full force of the law. A shameful double standard.